1. Field of Invention
The present invention generally relates to a refrigeration system of air conditioners and dehumidifiers, and more particularly relates to a refrigeration system, in which an enhancement device for removing condensation water from the evaporator is incorporated.
2. Related Art
As shown in FIG. 1, a refrigeration system, such as air conditioner or dehumidifier, generally includes a refrigerant compressor, a condenser, an expansion valve or capillary, and an evaporator to be composed of a refrigeration cycle. Liquid state refrigerant in low pressure and low temperature is compressed by the compressor into high pressure and high temperature gas state refrigerant, then cooled down through the condenser to be high pressure and medium temperature liquid refrigerant. The refrigerant further passes through the expansion valve or capillary to decrease its pressure into low pressure and medium temperature liquid refrigerant, then passes through the evaporator to dissipate its heat into low pressure and low temperature liquid refrigerant, and recycles to the compressor.
The common evaporator of an air conditioner or a dehumidifier is a fin-type heat exchanger. Such a heat-exchanger includes a plurality of flat fins arranged in parallel at a predetermined interval allowing air to flow through for heat transfer, and a plurality of heat transfer tubes perpendicularly inserted to the plurality of flat fins to which the temperature of refrigerant is transferred while being flown inwards, and at the same time, being contacted to air for heat-exchange. In tubes of the evaporator, the refrigerant expands to lose its temperature so as to cool down the air passing through the gaps between the fins. Water vapor contained in the air is then condensed into water, formed on the fins, drip by its weight and drain away.
But, the removal of water by its weight is rather slow because it takes a long time for the dripping formed on the fin to be heavy enough for falling. Therefore, the water staying on the fins decrease the heat-exchanging area, occupy gaps between the fins and retard the airflow. The less heat-exchanging area and the lower airflow rate increase burden of the cooling fan, lower the heat-exchanging rate and lower the operation performance of the whole system.
In this field, an eletrohydradynamic effect had been applied for improving heat-exchanging rate, which also improves the efficiency of water removal. An eletrohydradynamic device utilizes a low electrically conductive liquid flowing between two electrodes to provide an electric field of high voltage and low current. The electric field excites the surfaces of heat transfer to increase the efficiency. The common low electrically conductive liquid is chosen from CFC or other refrigerants. The factors that influencing the efficiency of heat transfer are electrical parameters (such as voltage, shape of and distance between the electrodes and direction of the electrical field), fluidic parameters (such as flow rate and thermophysical characteristics of the fluid) and the conditions of the heat transfer surface (such as surface structure, shape and size of the tube), etc.
A water removal enhancement device utilizing eletrohydradynamic effect is disclosed. As shown in FIG. 2, the device applicable to evaporator of an air-conditioning system includes a pulse power supply and an electrode mounted under the evaporator. The pulse power supply includes a flyback transformer and corresponding circuits for generating a high voltage and low current power supplied to the electrode and the evaporator. Negative electricity is thereby generated on the evaporator, and positive electricity on the electrode. The electrode is a metal wire or other similar metallic element located under the evaporator. Since water is a high dielectric constant material, the condensed water formed on the evaporator is charged with negative electricity by the evaporator. Therefore, the negative electrified condensed water is attracted the positive electrode and easily drop from the evaporator to the electrode and drain away. This device improves the water removal from the evaporator and improves the heat transfer efficiency of the air-conditioning system. But, the water removal is still unsatisfactory and a better device is demanded.